1. Field of the Invention
The present invention relates to a photographing technique, and more particularly to an automatic exposure control method.
2. Related Art
Currently, an overall brightness of an image when the image is shot is determined by exposure parameters such as an exposure speed level, an aperture value, an exposure time, and an exposure parameter corresponds to a brightness value. When an object is shot under backlight, the obtained image has a brighter part and a darker part. When a brightness of a background region is higher, a brightness of an object region is made to be relatively lower, that is, the brightness contrast between the background region and the object region is relatively large. Because of the high brightness contrast between the object region and the background region, when the brightness value is adjusted to make the object region become brighter, but the originally brighter background region becomes even brighter, the background region is over-exposed. The reason lies in that the adjustment of the brightness value not only affects the brightness of the background region, but also affects the brightness of the object region, so when the brightness value is adjusted to make the background region become brighter, the object region also becomes brighter; and when the background region is adjusted to become darker, the object region also becomes darker.
In U.S. Pat. No. 6,859,618, under a situation of without adjusting the brightness value, the object region is merely compensated by controlling the flash light. However, due to being restricted by the working scope of the flash light, the flash light may not reach the object region, such that the brightness is insufficient. If the exposure parameter can be controlled by adjusting the brightness value and the flash light, the expected effect of compensating the brightness of the object by the flash light may further achieved.